Detta projekt syftar till att undersöka den termiska rusningsprocessen hos ett litiumjonbatteri med en fluorfri elektrolyt och jämföra den med en kommersiellt använd fluor-innehållande elektrolyt. Battericellerna innehöll silikon-grafit som anod och LiNi0.6Mn0.2Co0.2O2 (NMC622) som katod. Den fluorfria elektrolyten var baserad på litium bis(oxalato)borat (LiBOB) i organisk lösning med additivet vinylen karbonat(VC). Det jämfördes med en fluor-innehållande elektrolyt med LiPF6 i samma organiska lösning tillsammans med VC och fluoroetylene karbonat (FEC). De termiska stabilitetstesterna utfördes med Accelerating Rate Calorimetry (ARC) och Differentiell svepkalorimetri (DSC). Både knappceller och pouchceller har undersökts med hjälp av ARC. Trots flera försök med olika uppställning kunde den termiska rusningen inte bli detekterad för någon av celltyperna, med slutsatsen att en störremängd aktivt material behövs. Istället användes DSC för att undersöka de termiska reaktionerna hos batteri-komponenterna. Resultaten visade att anoden var mer termisk stabil med den fluorfria elektolyten, medan samma elektrolyt visade mindre termisk stabilitet på katoden. Vidare undersökningar behövs dock för bekräftelse av katoden. / This project aims to investigate the thermal runaway process of fluorine-free lithium ion battery cells and to compare this with a commercially used fluorinated electrolyte. The cells consisted of a silicon-graphite composite anode and a LiNi0.6Mn0.2Co0.2O2(NMC622) cathode. The non-fluorinated electrolyte used was based on lithiumbis(oxalato)borate (LiBOB) in organic solvents with the additive vinylene carbonate(VC). Moreover, the fluorinated electrolyte consisted of LiPF6 in the same organic solvents together with VC and fluoroethylene carbonate (FEC). The thermal stability measurements have included Accelerating Rate Calorimetry (ARC) and Differential Scanning Calorimetry (DSC). Moreover, both coin cells and pouch cells have been examined by ARC. However, thermal runaway could not be detected for either type of cells, concluding that a greater amount of active material was needed. In order to measure the thermal reactions of the battery components, DSC was used. These results concluded that the anode was more thermally stable with a non-fluorinated electrolyte. However, the thermal stability appeared to be lower for the cathode, therefore, further investigation is needed for confirmation of the cathode.

Předkládaná práce se zabývá výzkumem nových materiálů a metod přípravy gelových polymerních elektrolytů (GPE) na bázi methakrylátů, které lze zejména vzhledem k jejich mechanickým vlastnostem s výhodou využít při konstrukci elektrochromních (EC) prvků.

Mgr. Martina Nádherná PhD. Thesis Applications of ionic liquids in electrolytes for amperometric gas sensors and Li-ion batteries SUMMARY The dissertation presents the results of preparation and characterisation of new aprotic electrolytes based on ionic liquids for the solid-state electrochemical gas sensors and for the electrochemical energy storage devices - secondary lithium-ion batteries. In the part dealing with the solid-state amperometric sensor for NO2 research was aimed at development of new solid electrolyte. This electrolyte is developed as a system of ionic liquid embedded in the structure of a polymer, when the ionic liquid joints the properties of a solvent and a dissolved salt. The electrolyte therefore does not contain any volatile component and is long-term chemically and electrochemically stable. Several series of electrolytes were prepared with different polymers or macromonomers and imidazolium-based ionic liquids. The composition, especially the polymer-IL ratio was optimized. The electrolytes were successfully tested in a solid-state NO2 sensor with a gold minigrid serving as the indicating electrode. The research included the determination of basic electrochemical parameters and study of the sensor behaviour under different conditions. The influence of atmosphere humidity,...

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Many countries including Sweden are planning to replace fossil fuel-based vehicles with electric vehicles. This is one of the main reasons that companies all over the world are investing more and more money in the development of lithium-ion batteries, for electric vehicles. There are several different risks with the conventional lithium-ion batteries including the high flammability of the electrolytes, which can lead to high heat release rate, risk of explosion and high toxicity in the form of hydrogen fluoride gas. The hydrogen fluoride is lethal even at low concentration. These potential risks are based on the structure of the flammable electrolytes inside the lithium-ion batteries. Because of that, there is a big interest in finding an electrolyte with similar battery performance and better fire properties as compared with the conventional electrolytes commercially available on the market.   The intent with this work is to investigate the fire properties of different halogen-free electrolytes. The two newly developed salts Li[MEA] & Li[MEEA] as well as the available salt Li[BOB] will be compared with the commercially used halogen-containing electrolyte based on lithium hexafluorophosphate (LiPF6) salt.   Physical and electrochemical properties of these electrolytes such as solubility in different organic solvents, density, viscosity, ionic conductivity and electrochemical window will be studied in the first step. The electrolytes showing the most promising electrochemical properties will then be further investigated regarding fire properties, heat release rate, flash point and toxicity. The electrolytes will be compared with the conventional electrolyte containing LiPF6.   Li[BOB] was not dissolved in the solvents with the strongest dissolving properties, therefore it was not further tested. The electrolytes that were tested regarding fire properties were Li[MEA] and Li[MEEA] with the organic solvents of ethylene carbonate and dimethyl carbonate. Ionic liquid was also added to Li[MEEA] to investigate how it affected the fire properties for the electrolyte.   When examine the heat release rate for the newly developed salts, as well as LiPF6, it was observed that the highest peaks were similar to each other. The combustion time for the electrolyte containing LiPF6 was noticeable shorter than for the other three electrolytes. This is likely due to the fluorine content in LiPF6. The electrolytes undergoing the cone calorimeter test in this work was not charged so therefore the peaks of the heat release rate may look different. For further studies, it could be of interest to construct a complete lithium-ion battery using these electrolytes to see how the battery cells and the electrolytes behave in different set of charges.   Another essential point, is the ignition time that showed varied times for the tests containing Li[MEEA] together with the organic solvents and with the added ionic liquid. This is an interesting result that probably can be explained by the homogeneity of the electrolyte. The homogeneity was only verified with the help of the human eye and therefore it may not be fully dissolved.   The flashpoint for the different mixtures of electrolytes showed values of interest where the electrolyte containing ionic liquid that showed the lowest flashpoint. This was unexpected concerning that these types of additives are common for improving the fire resistance capacity.   The key aspect discussed when analyzing the result from the FTIR spectroscopy was how the Li[MEA], Li[MEEA] and LiPF6 salts varied. The ones that did not have any fluorine in its structure resulted in production of carbon dioxide. However, the electrolyte containing fluorine resulted, as expected, in values of hydrogen fluorine and carbon dioxide but also other combustion products that was hard to determine.   These salts and electrolytes need to be further studied and tested to see if it is possible to use them in an actual lithium-ion battery. Besides further tests of the salts and ionic liquid tested in this work, it is important that the work with conventional and newly developed electrolytes aims for improvements in fire resistance as well as toxicity. / Många länder inklusive Sverige planerar att byta ut fordon som använder fossila bränslen mot elfordon. Detta är en av huvudanledningarna till att företag runt om i världen satsar mer och mer pengar på att utveckla litiumjonbatterier för elfordon. Litiumjonbatterier medför en del risker såsom hög värmeutveckling, brandfarliga vätskor, risk för explosion och toxiska gaser samt produceringen av vätefluorid. Redan vid låga koncentrationer är vätefluoriden dödlig. Riskerna baseras på strukturen av elektrolyten som finns i litiumjonbatteriet. På grund av dessa risker så är det intressant att utveckla en elektrolyt som har liknande batteriegenskaper men bättre brandegenskaper än de elektrolyter som finns och används idag.   I detta arbete har brandegenskaper för olika halogenfria elektrolyter testats. De två nyutvecklade salterna Li[MEA] & Li[MEEA] har tillsammans med det existerande saltet Li[BOB] jämförts med det kommersiella saltet litium hexafluorfosfat (LiPF6) som används till många elektrolyter i dagens litiumjonbatterier.   De fysiska och elektrokemiska egenskaperna såsom löslighet i organiska lösningsmedel, densitet, viskositet, jonkonduktiviet och elektrokemiskt fönster har testats för elektrolyterna i den första delen av arbetet. Elektrolyterna som uppvisade de mest lovande elektrokemiska egenskaper har även testats med avseende på brandegenskaperna, så som värmeutveckling, flampunkt och toxicitet. Elektrolyterna jämfördes mot den vanligt förekommande elektrolyten som innehåller litium hexafluorfosfat.   Saltet Li[BOB] löstes inte i lösningsmedel med bra lösningsegenskaper, vilket var anledningen till att det inte genomfördes ytterligare tester på den. Elektrolyterna som det genomfördes tester på avseende på brandegenskaper innehöll Li[MEA] och Li[MEEA] tillsammans med de organiska lösningsmedlen etylenekarbonat och dimetylkarbonat. För Li[MEEA] tillsattes det även jonvätska för att undersöka hur jonvätskan påverkar brandegenskaperna för elektrolyten.   När värmeutveckling för det nyutvecklade salterna och LiPF6 undersöktes, så uppvisade de liknande värden. Anmärkningsvärt var dock att förbränningstiden för LiPF6 varade under en kortare period i jämförelse med de tre andra elektrolyterna. En trolig orsak till detta är att LiPF6 innehåller fluor. Elektrolyterna som provades i konkalorimeter i detta arbete var ej laddade, vilket kan medföra att värmeutvecklingen kan se annorlunda ut vid ett laddat tillstånd. För framtida studier kan det vara intressant att konstruera ett komplett litiumjonbatteri, för att se hur elektrolyterna fungerar och påverkas, beroende på laddningsnivå.   Antändningstiden för Li[MEEA] blandat med de organiska lösningsmedlen tillsammans med jonvätska varierade mycket. Detta är ett intressant resultat, som förmodligen kan förklaras av homogeniteten på elektrolyten. Homogeniteten verifierades enbart okulärt, vilket inte säkerställer att jonvätskan har löst sig fullständigt i elektrolyten.   Resultat för flampunkten för det olika elektrolyterna var intressant, då elektrolyten som innehöll jonvätska visade på lägst flampunkt. Detta var oväntat då tillsatser som jonvätska brukar förbättra brandmotståndet.   Resultatet för FTIR-spektroskopin analyserades för att se hur Li[MEA], Li[MEEA] och LiPF6 skiljde sig åt. De elektrolyter som inte innehöll fluor, producerade bara koldioxid. Medans elektrolyten som innehöll fluor producerade, som väntat, vätefluorid och koldioxid, men även andra gaser som var svåranalyserade.   De framtagna elektrolyterna i detta arbete behöver studeras vidare och fler tester bör genomföras för att se om det finns en möjlighet att använda dem i faktiska litiumjonbatterier. Förutom att testa elektrolyterna i just detta arbete är det viktigt att forskningen kring brandegenskaper och toxiska egenskaper för elektrolyter fortsätter i framtiden.

This paper deals with the construction of photoelectrochemical cell, used for detection of ultraviolet radiation as a UV sensor. Photoelectrochemical cell consists of three layers, layer of photoactive semiconductor titanium dioxide, carbon electrodes and poly(vinyl alcohol) polymer electrolyte. The sensor layer enables the detection of UV radiation with the subsequent generation of photocurrent. Material printing techniques, such as screenprinting, pad printing and inkjet printing were used to produce the cell. Gel electrolyte was characterized by optical microscopy and rheometry. Sensor functionality was verified by use of electroanalytical techniques.

This thesis deals with novel electrolytes for magnesium batteries. Prepared electrolytes were composed of affordable solvents and chemicals, which can be handled at normal laboratory conditions. Specifically, solutions of tetrahydrofurane and dimethylsulfoxide with magnesium chloride, aluminium chloride, nitrilotriacetic acid and disodium ethylenediaminetetraacetic acid, were prepared. To determine electrolyte ability of magnesium stripping and deposition, the cyclic voltammetry was used. The kinetics of electrochemical reactions in terms of polarization resistance was studied by electrochemical impedance spectroscopy. Based on scanning electron microscopy and EDS analysis, the effect of atmospheric oxygen and humidity on magnesium electrode corrosion during cycling was discussed.

The thesis includes the basic principles of lead-acid, NiCd, NiMH and Li-Ion batteries. There is a description of their features and phenomena that processes in the batteries during charging and discharging. The most important part is devoted to dynamic models of these types of batteries, the parameters that are necessary for their modeling, and testing of absolute error models. Further, the model in Matlab was created which allows the simulation of the GRID-OFF photovoltaic system using the battery model.

Lead-acid battery serves as the primary power source for vehicles. The total lifetime is determined by the parameters identified in the production, but also handling the operation and maintenance. This work deals with the effect of additives in the electrolyte added before and after the formation of cells lead-acid battery. The work deals with the influence of these additives during cyclic mode.

This diploma thesis focuses on study of positive electrode materials for Li-Ion batteries. Our aim are intercalation materials whose are really perspective materials whose are widely used in this case. The theoretical part of my thesis focus on basic study of Li-ion batteries and their parameters. We studied charging and discharging processes. AFM and SEM were used as additional techniques for study LiCoO2 a Li0,975K0,025CoO2. We tested lifetime and stability of electrode as a perspective material for electrode for Li-ion batteries.